intel 2102 RAM chips installed on the SOL-20 motherboard. Note some read equiv name AM91L02. I tested and swapped out two of these to resolve the 909090 pattern error displayed on the screen. Click to view larger view.

The last time I used my SOL-20 it was fine, other than the keyboard. I set up my SOL-20 this weekend to see how it would work with the OAE OP-80A papertape reader. I never got that far as when I fired up the machine I was greeted with a screen full of 909090 rather than a SOLOS prompt.
I took a look at the troubleshooting section of the Processor Technologies Sol Systems Manual, page 250. It suggested which TTL chips to test, but I had already checked and ruled out those, so I next tested t">...[ read more ]

The 1980 Cromemco 3102 terminal was made by the Beehive corporation and re-badged for Cromemco. Click image for larger view.

Pictured is the 3102 Terminal with a 1981 Cromemco System One. The terminal has a larger footprint than the computer. In real life, the terminal would sit on the desk and the computer was probably installed under the desktop in a custom enclosure. Click image for larger view.

Snapshot in mid motion. Need to diagnose cause of a rippling screen that reminds me of a flag waving in a slow wind. Click image for larger view.

See video:
https://www.face...7003536391245/
Going with assumption the brightness, contrast, vertical hold are ok and the screen does not shrink. It looks like a flag slowly rippling in the wind because a cap(s) is failing but not failed entirely.
Probably unrelated is the fact that I had to bang on the chassis when the system was first powered on in order to get the display to show anything. There may also be a cracked solder joint somewhere.
Conclusion - The entire display needs to be worked over,">...[ read more ]

This OSI Challenger 1P came to Kennett Classic as a donation. It has some interesting mods installed including a "BREAK/No BREAK" mod and a "Tape" mod. Click image for larger view.

A "Sup-R-Mod" has been installed so that the computer can be attached to a black and white television on channel 33. Not any TV will work, only the old style sets without a certain type of synch (forget the details) such as the pictured Sony PVJ-51RU I picked up from a computer rescue last year. Click image for larger view.

NEXT: Open the system and work through the mods, try to find matching documentat">...[ read more ]

Making heads or tails of the LGP-30 SIMH simulator written for the Royal Precision Electronic Computer model LGP-30 is a worthy challenge for any early 21st Century computer user. Built by the Royal McBee Corporation and first sold in late 1956, this machine is mentioned by sources to be the first personal computer - i.e. the first electronic computer designed for one person to use / operate. The Friden Flexowriter is the I/O device. The Flexowriter is similar to the ASR 33 Teletype in that it included both a typewriter/printer and a papertape storage/reader function.
Operational">...[ read more ]

Turned my attention to a dead CBM 2040 drive. Totally dead, no power. First thing I checked was the fuse, but it was ok. Next I checked the voltages coming into the transformer, nothing. Click image for larger view.

Found the problem. The person who serviced this drive whatever years ago attached one of the power switch wires to the outer post of the fuse holder, but did not make sure that there was an actual connection to the fuse itself. Almost looks like a homebrew cigar ring or something. Click image for larger view.

Photo of a Honeywell u-COMP DDP-516 control console. The orange color scheme was used in the 1966~68 u-COMP models, see early advertisements. Many people know of the "kitchen computer", the 516 is the same thing, same instruction set as the DDP-316 (H316). If the 316 is the Kitchen Computer, the 516 is the "business" model. This console would sit on the operator's desk, or on top of the computer cabinet, which stood about 4 feet tall (need to check that). The operator would use the console buttons and switches as one would use a front panel. There is also a blue cover version of this consol">...[ read more ]

Computer Magic?
"... No, it's a well know face that has been precisely blurred by a computer. It's part of an experiement by Leon D. Harmon at Bell Laboratories to learn the least amount of visual information a picture may contain and still be recognizable. .."
- The LINKING RING vol 51, NO. 8 August, 1971.">...[ read more ]